Effects of different matrixes on the dosimetric response of α-terthiophene films from the kGy to MGy range

Abstract Films of polymethylmethacrylate (PMMA) and polystyrene (PS) containing α -terthiophene (3T) undergo a radiochromic effect when exposed to electrons and gamma rays. The films turn either red–green or red, due to the formation of oligomeric radical cations. In both matrixes, absorbance at 465 nm grows linearly with dose when α -terthiophene concentration reaches 12%. Explored range goes up to ∼2×10 6  Gy, with dose rates spanning over three orders of magnitude. Concerning their application as dosimeters, a higher sensitivity characterises the 3T–PMMA moiety, suggesting its suitability from the kGy range up to 1 MGy. Above this value films become fragile. 3T–PS films are less sensitive, but more radiation resistant. Therefore they better suit the medium-to-high dose dosimetry range. Dose rate influences the response sensitivity in a complex way, however above 80 and up to 3.6×10 4  Gy/min an approximate linearity exists between log (dose rate) and sensitivity, as in the analogous cellulose triacetate system.